Project at a Glance

• Owner: City of Ocean Beach / Local Municipality

• Client: Galvin Brothers

• Location: Ocean Beach Fire Island New York

• Work Type: Deep-Well Dewatering

Project Overview

Tri-State Dewatering successfully designed and operated a high-capacity deep-well dewatering system for a new pump station excavation extending 30 feet below sea level. Situated directly adjacent to the Atlantic Ocean, the project required robust groundwater control to manage extreme inflow and ensure a safe, stable work environment.

Project Overview

Tri-State Dewatering was selected to design, install, operate, and maintain a high-capacity dewatering system for the construction of a new pump station at Ocean Beach. The project required groundwater control for a deep excavation extending to Elevation -29 feet, nearly 30 feet below sea level.

Located immediately adjacent to the Atlantic Ocean, the site presented extremely challenging groundwater conditions. The combination of deep excavation, highly permeable coastal soils, and direct hydraulic influence from the ocean demanded a robust and carefully engineered dewatering solution to maintain a safe and stable excavation throughout construction. Tri-State designed and installed a deep-well dewatering system within the sheeted excavation to achieve the required groundwater drawdown. The system was engineered to lower groundwater levels sufficiently to allow construction activities to proceed safely and efficiently at the design excavation depth.

Project Challenges

The Ocean Beach Pump Station excavation represented one of the most demanding dewatering applications in the region. Excavation depths approached 30 feet below sea level, creating substantial groundwater inflow pressures. In addition, the proximity of the excavation to the ocean resulted in continuous recharge of groundwater into the work area.

To minimize groundwater intrusion, steel sheet piling was installed around the excavation perimeter to a depth of approximately 60 feet below grade, creating a partial groundwater cutoff. While the sheeting significantly reduced groundwater inflow, the excavation still required a large-scale dewatering system capable of maintaining groundwater levels well below the excavation bottom. The project demanded continuous operation and monitoring to ensure excavation stability, protect adjacent infrastructure, and maintain construction progress despite the aggressive groundwater conditions.

Results